Initial Prostate Health Index (phi) and phi density predicts future risk of clinically significant prostate cancer in men with initial negative prostate biopsy: a 6-year follow-up study.

BACKGROUND

Men with elevated prostate-specific antigen (PSA) and initial negative prostate biopsy may have risk of prostate cancer (PCa) in the future. The role of Prostate Health Index (phi) in determining future PCa risk has not been studied before. This study aims to investigate the role of initial phi and phi density in predicting future PCa risk in men with initial negative biopsy.

METHODS

Five hundred sixty nine men with PSA 4-10 ng/mL were recruited between 2008 and 2015 for prostate biopsy with prior phi. Electronic clinical record of men with initial negative biopsy was reviewed. Patients and follow-up doctors were blinded to phi. Kaplan-Meier curves were used to analyze the PCa-free survival in different baseline phi and phi density groups.

RESULTS

Four hundred sixty-one men with complete follow-up data were included. Median follow-up is 77 months. PCa and HGPCa was diagnosed in 8.2% (38/461) and 4.8% (22/461) of cohort respectively. A higher baseline phi value was associated with PCa (p = 0.003) and HGPCa (p < 0.001). HGPCa was diagnosed in 0.6% (1/163) of phi < 25, 4.6% (9/195) of phi 25-34.9, and 11.7% (12/103) of phi ≥ 35 (p < 0.001). HGPCa was diagnosed in 0% (0/109) and 21.0% (13/62) with phi density of <0.4 and ≥1.2, respectively, (p < 0.001). Kaplan-Meier curves showed phi and phi density predicted PCa and HGPCa diagnoses (log-rank test, all p ≤ 0.002).

CONCLUSIONS

Initial phi or phi density predicted 6-year risk of PCa in men with initial negative prostate biopsy. Men with higher phi (≥35) or phi density (≥1.2) need closer follow-up and repeated investigation, while men with lower phi (<25) or phi density (<0.4) could have less frequent follow-up.